I don't know if it's okay to load cases that were standard .38 Specials to +P pressures, I never had that come up before. If the base of factory-loaded +P loads are in the same cases as standard .38 Specials are, then the primers come into question. I don't know if standard .38 loads use the same primers as +P loads but whether they do or not ought to be checked out.

I think Bailey Boat wrote the most important issue here: "With all of that said, I purposely developed the loads in 357 cases just to make sure they stayed out of 38's" which means something to me since my favorite CCW is a S&W Model 36 snubby which is not strong enough for +P's and certainly not up to greater pressures than that.